Agamemnon Crassidis is a mechanical engineering professor at the Rochester Institute of Technology and the academic director of upstate New York’s private drone research alliance, NUAIR. He reviewed the crash's accident report for The Innovation Trail.

GPS and internal navigation system failures on drones are their most common issue, he says.

"I’m assuming what happened was, once it lost its location, it caused the drone to go into an emergency mode and it looks like those emergency system backup modes failed as well," he said.

The drone’s emergency backup autopilot mode is designed to steer away from populated areas on its way back to base, but Crassidis says with navigation systems down, some luck may have factored into the drone still being over water when it went down.

"In terms of the sensor not being able to locate the position, then essentially the unmanned aircraft system had no idea where it was," he said, "and we got lucky it didn’t crash into a populated area."

"I can't recover it," the pilot said as the MQ-9 went into a flat spin.

Credit U.S. Air Force accident report

The Air Force says a bad right turn while on autopilot sent the drone into an unrecoverable flat spin.

Crassidis says a drone under computer control is only as good a flyer as the sensors it has on board.